day 02

02/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"flag"
 	"fmt"
+	"math"
 	"os"
 	"regexp"
 	"strconv"
@@ -10,19 +11,18 @@ import (
 )
 
 var (
-	inputFile = flag.String("input", "input.txt", "input filename")
-	nRegex    = regexp.MustCompile(`(?m)\d`)
-	reMap     = map[string]string{
-		"one":   "1",
-		"two":   "2",
-		"three": "3",
-		"four":  "4",
-		"five":  "5",
-		"six":   "6",
-		"seven": "7",
-		"eight": "8",
-		"nine":  "9",
-	}
+	inputFile   = flag.String("input", "input.txt", "input filename")
+	subsetRegex = regexp.MustCompile(`(?mi)(\d+)+\s(\w+)([,;]?)`)
+	startRegex  = regexp.MustCompile(`(?mi)Game\s(\d+):`)
+)
+
+const (
+	BlueCube  = "blue"
+	GreenCube = "green"
+	RedCube   = "red"
+	MaxRed    = 12
+	MaxGreen  = 13
+	MaxBlue   = 14
 )
 
 func main() {
@@ -32,61 +32,64 @@ func main() {
 		panic(err)
 	}
 
-	var sum int
+	var sum, powSum int
 	for _, line := range strings.Split(string(input), "\n") {
 		if strings.TrimSpace(line) == "" {
 			continue
 		}
 
-		// forward-scan for spelled digits
-		var forwardReplacedLine, backwardReplacedLine string
-		for i := 0; i < len(line); i++ {
-			forwardReplacedLine += string(line[i])
-
-			// replace all potential spelled out digits by their non-word counterpart (e.g. "one" -> "1")
-			for key, val := range reMap {
-				forwardReplacedLine = strings.ReplaceAll(forwardReplacedLine, key, val)
-			}
-		}
-		fmt.Println(forwardReplacedLine)
-
-		// backward-scan for spelled digits
-		for i := len(line) - 1; i >= 0; i-- {
-			if i == len(line)-1 {
-				backwardReplacedLine = string(line[i])
-			} else {
-				backwardReplacedLine = string(line[i]) + backwardReplacedLine
-			}
-
-			// replace all potential spelled out digits by their non-word counterpart (e.g. "one" -> "1")
-			for key, val := range reMap {
-				backwardReplacedLine = strings.ReplaceAll(backwardReplacedLine, key, val)
-			}
-		}
-		fmt.Println(backwardReplacedLine)
-
-		// find single digits in forward-replaced line
-		firstMatch := nRegex.FindAllStringSubmatch(forwardReplacedLine, -1)
-
-		// find single digits in backward-replaced line
-		lastMatch := nRegex.FindAllStringSubmatch(backwardReplacedLine, -1)
-
-		// get first matchgroup, first match (aka first digit in forwardReplacedLine)
-		first := firstMatch[0][0]
-
-		// get last matchgroup, first match (aka last digit in backwardReplacedLine)
-		last := lastMatch[len(lastMatch)-1:][0][0]
-
-		fmt.Println(first + last)
-
-		// concatenate digits and convert the resulting string to int
-		asInt, err := strconv.Atoi(first + last)
+		// find id
+		idMatch := startRegex.FindAllStringSubmatch(line, -1)
+		id, err := strconv.Atoi(idMatch[0][1])
 		if err != nil {
 			panic(err)
 		}
 
-		sum += asInt
+		// find sets of digit + color + separator (e.g. "3 blue,")
+		subsets := subsetRegex.FindAllStringSubmatch(line, -1)
+
+		var red, green, blue int
+		var minRed, minGreen, minBlue int
+		possible := true
+
+		for _, subset := range subsets {
+			cubeAmount, err := strconv.Atoi(subset[1])
+			if err != nil {
+				panic(err)
+			}
+
+			// add cube amount to set
+			switch strings.ToLower(subset[2]) {
+			case BlueCube:
+				blue += cubeAmount
+			case GreenCube:
+				green += cubeAmount
+			case RedCube:
+				red += cubeAmount
+			}
+
+			// end of set reached
+			if subset[3] == "" || subset[3] == ";" {
+				if red > MaxRed || green > MaxGreen || blue > MaxBlue {
+					possible = false
+				}
+				minBlue = int(math.Max(float64(minBlue), float64(blue)))
+				minRed = int(math.Max(float64(minRed), float64(red)))
+				minGreen = int(math.Max(float64(minGreen), float64(green)))
+				red = 0
+				blue = 0
+				green = 0
+			}
+		}
+
+		// end of game reached
+		powSum += minRed * minGreen * minBlue
+		if possible {
+			fmt.Printf("%d possible\n", id)
+			sum += id
+		}
 	}
 
-	fmt.Println(sum)
+	fmt.Printf("Sum of IDs: %d\n", sum)
+	fmt.Printf("Sum of the power of sets: %d", powSum)
 }